Controllable reversible pitch propeller system



Dec. 7, 1954 J, NICHQLS 2,696,270

CONTROLLABLE REVERSIBLE'PITCH PROPELLER SYSTEM Filed Jan. 19, 1948 4 Sheets-Sheet 1 Dec. 7, 1954 H 1 NlCHQLs 2,696,270

CONTROLLABLE REVERSIBLE PITCH PROPELLER SYSTEM Filed Jan. 19. 1948 4 Sheets-Sheet 2 FIG. 5

Dec. 7, 1954 H. J. NICHOLS 2,696,270

CONTROLLABLE REVERSIBLE FITCH PROPELLER SYSTEM Filed Jan. 19, 1948 4 Sheets-Sheet I5 INVENTOR HARRY J. NICHOLS,

ATTOR NEY Dec. 7, 1954 H. J. NlcHoLs 2,696,270

CONTROLLABLE REVERSIBLE PITCH PROPELLER SYSTEM Filed Jan. 19, 1948 4 sheets-sheet 4 DAR.

INVENTOR HARRY J. NICHOLS B* #wwwa ATTORNEY United States attent VC) CONTROLLABLE REVERSIBLE PITCH PROPELLER SYSTEM Harry J. Nichols, Point Pleasant, N. J. Application January 19, 194s, serial No. 3,025

2 claims.' (ci. 17o-160.29)

This invention relates to controllable reversible pitch propeller systems and more particularly to such propeller systems for use on motor boats, and has for its main object the provision of a propellerof the character described in which the pitch of the blades can be readily and accurately varied, and also reversed, while the propeller is in rotation under load.

Another object is to provide an exceptionally simple, compact, and durable pitch changing mechanism which is economical to manufacture, easy to install and service, and which embodies pitch limiting and pitch indicating devices, and other practical features to facilitate operation by unskilled and non-technical operators.

Another object is to provide a strong and rugged blade turning mechanism adapted to be housed within a propeller hub of relatively small diameter which will have a minimum of working parts and will hold the blades rigidly, thereby avoiding any possibility of flutter or vibration of the blade in operation due to excessive back-lash or elasticity; and which will also automatically lock the blades against being turned by external forces at any position of pitch adjustment.

Another object is to provide a torque-amplifying actuating mechanism for driving the blade turning mechanism which is self-energizing, that is it derives its operating torque from the propeller shaft; and which is adapted for operation by remote control.

Another object is to provide a pitch varying mechanism of adequate angular range, including reversing, which is capable of changing the pitch in micrometric increments when desired, yet also is capable of changing the pitch at a rapid rate for maneuvering and meeting emergencies.

Yet another object is to provide a pitch changing mechanism in which the actuating mechanism is relieved of any strain except when the pitch is being changed, thus reducing wear and `enabling relatively light mechanical parts to be employed.

A further object is to provide a mechanical pitch limiting device to prevent the pitch from being varied beyond the proper operating range, and a pitch indicating device to indicate visually at all times the pitch of the blades.

With these and other objects in view, as `vell as other advantages incident to the improved construction, the invention consists in various novel features and combinations thereof set forth in the claims with the understanding that the several necessary elements constituting the same may be varied in proportion and arrangement with- 'out departing from the nature and scope of the invention as defined in the appended claims.

To enable others skilled in the art to comprehend the underlying features of this invention that they may embody the same by suitable modifications in structure' and relation to meet the various practical applications contemplated by the invention, drawings showing a preferred embodiment `of the invention form part of this disclosure, and in such drawings like characters of reference denote corresponding parts in the several views in which:

v. Fig. 1 is aside elevation in part at axial section of a hub assembly embodying certain features of the invention.

Fig. 2 is an end view in partial transverse section of the assembly of Fig. l, the partial section being taken substantially at plane -2-- of Fig. l.

Figs. 3 and 4 are top and end views respectively of the novel wedge member of the invention.

Fig. 5 is a longitudinal View in partial axial section of the power unit assembly of the invention.

2,696,270 Patented Dec. 7, 1954 Considered as a whole, and referring generally to the drawings, the system of the invention comprises two main units; namely, a propeller assembly including a hub having axially rotatable blades and a mechanical movement mounted within the hub for turning the blades axially in unison, as shown in Figs. l to 3 inclusive; and a power unit including torque amplifying mechanism for powering the mechanical movement in the hub, as shown in Figs. 5 to 7 inclusive. A tubular propeller shaft and a torque shaft mounted coaxially therein operatively connect these two main units.

A pitch limiting device for restricting the pitch range is embodied in the power unit.

The invention also includes a remote control system, as shown in Figs. 5 and 8, for controlling the pitch from a remote station, including means for indicating the pitch visually.

Propeller assembly Referring now to the drawings in detail and particularly to Figs. l to 4, the propeller assembly comprises an integral hollow hub 10 xed tightly to the outboard end of the tubular propeller shaft 30 in any desired manner, and blade turning mechanism operatively mounted therein. The hub-is provided with ablind axial bore extending from the inboard end, and symmetrically disposed radial open sockets, one for each blade. Blades 20, each having a circular boss and a cylindrical root, are rotatably secured in the radial sockets. Each blade is provided with a anged journal 21 mounted concentrically on the root and fixed to the blade by means of cap screws 28 extending through the boss as shown. Each journal 21 is mounted in a combination radial and double thrust bearing comprising, bearing ring 12 locked in the socket by a retainer ring 13, retainer ring cover washer 14, spring sealing cup 15, and a thrust washer 16 cemented to the blade boss. Sealing cup 15 has an outwardly springing lip adapted to seal tightly in the bore of the socket, and an arched, resilient ring section bearing against thrust washer 16. The construction shown is such that when each blade is bolted tight to its journal, the arched section of sealing cup 18 is compressed elastically, thereby to provide an exterior seal for the blade mounting and to preload the thrust bearings, the latter action preventing shake or wobble of thev blades.

The blades can be turned about their axes in unison to vary their pitch by means of a novel mechanical movement for applying a torque couple to each blade. This movement includes a prismatic sliding cam 24 having equilateral faces, one for each blade, provided with a pair of oppositely inclined cam grooves. (See Figs. 3 and 4.) A pair of crank pins 22 extending from the face of each blade journal 21 engage with each pair of cam grooves and are forced to move therein as followers upon axial translation of the cam 24. Roller sleeves 23, or slipper blocks in lieu thereof if desired, are mounted on the crank pins to reduce wear in operation, in well-known manner. Cam 24 is also provided with a threaded axial bore and is slidably mounted in the axial bore of the hub. It is translated axially in operation by an axial screwshaft 25 mating rotatably therein, this pair constituting a screw-jack.

The mechanical movement just described applies upon v yoperation a torque couple to turn the blades axially, therenegligible back-lash, thus avoiding the possibility of shake and consequent blade vibrations. Moreover, cam 24 is slidingly supported iri the bore so that it cannot turn or move sidewise, hence no additional means for guiding it is necessary. lt is thus thought evident that the blade turning mechanism provides outstanding advantages in combination with other features of the construction of the in- Vention.

Power unit Referring now to Figs. to 7 inclusive, the assembly there s hown provides the four-fold function of connecting the drive shaft 80 in driving relation to propeller shaft 30; housing torque amplifying gearing for driving jack-screw 25; housing torque transmission gearing for driving the torque amplifying gearing; and providing a two-way thrust bearing and end bearing for jackscrew 25, all in a space but little larger in diameter than an ordinary ange coupling and four shaft diameters in length.

The propeller shaft is provided with a demountable flange as shown, or that provided by the engine maker, to enable the propeller shaft to be drawn outboard from its bearings. No change need be made in the drive shaft or its flange.

A coupling shaft 46 having a demouritable flange 41 is provided for coupling drive shaft 80 to propeller shaft 30 and to mount the gearing for powering the jackscrew 25. The power gearing comprises three trains of gears connected in series; namely two sections of differential planetary gearing (termed herein the ahead and reverse sections) for deriving bi-directional operating torque from the uni-directional shaft torque, and torque transmission gearing for applying the derived bidirectional torque to jack-screw 25.

Each section of the planetary gearing includes an independently rotatable planet carrier 5t), 53 carrying double planet pinions 51, 54 respectively, each carrier `constituting the actuating member of its respective gear train. cyclic trains having equal but opposite speed reduction ratios. Two sets of piston type hydraulic brakes 6l, 62 each having three radial brake cylinders, are provided to slow down or stop one or the other of their associated planet carriers for changing the pitch.

The operation of the planetary gearing is as follows: Normally the gearing revolves bodily with the shafts without gear action. When one or the other of the planet carriers is slowed down by the action of the associated brakes, its associated gear train generates amplified torque in one direction or the other which turns 'ring gear 55 relative to the shaft. Ring gear 55 drives xed pinions 56 which pinions in turn drive sun gear 26, thereby rotating jack-screw 25.

it should be noted that when the first planet carrier is retarded by its brakes, planet pinions 51 generate differential rotation between fixed first gear and intermediate gear 52, while the other set of planet pinions serve to lock the intermediate gear 52 to the third gear 55. But when the second planet carrier is retarded by its brakes, planet pinions 5l serve to lock intermediate gear 52 to fixed gear 45, while planet pinions 54 gen- Vcrate differential rotation between intermediate gear 52 and driven ring gear 55.

The planetary gearing described constitutes a powerful torque amplifier whereby a relatively small braking force is enabled to control a large actuating torque derived from the engine power. Since the power required to change the pitch is of the order of a few per cent of the engine power, the brakes can be quite small compared to those necessary in ordinary reverse gearing.

An important result is that the rate of pitch change `depends on the degree of brake action up to a certain point. Thus, when weak braking force is applied so as l,to merely slow down one of the planet carriers, the pitch is slowly changed; but if enough brake force is applied to stop a planet carrier, the pitch is changed rapidly. This feature promotes flexibility and ease of control, thereby facilitating maneuvering.

Pitch limit device The planetary gear trains are differential epiof the cam 24 might damage the mechanism. Hence a mechanical device is provided to limit the pitch range at the input end. This device nullities the action of one or the other of the brakes when certain pitch limits are approached.

Referring now to Figs. 5 and 7, a controlled locking device is provided for each planet carrier. The locking elements are two sets of three radially disposed ball wedges 38, set in radial holes in coupling shaft 40. The control element is a slidable threaded mandrel 36, having a double coned portion (see Fig. 5), constituting a wedge and actuated by jack-screw 25. A feather element 37 prevents relative rotation between mandrel 36 and shaft 40.

Normally, the balls are loose in non-operative position as shown in Fig. 7. When a pitch limit is approached, one set of balls is moved into locking position by one or the other of the cones of the mandrel. Should the operator fail to release the brakes at the proper time, or attempt to apply the brakes improperly so as to exceed either limit, the balls are wedged forcibly between the cone of the mandrel and the bore of the associated planet carrier 50 or 53. Thereupon, further relative rotation of the associated planet carrier is stopped, The locking force exerted by the balls must of course exceed the braking force, which is not difficult to accomplish due to the small braking force required. The other planet carrier meanwhile remains free to enable the pitch to be changed in the proper direction. When mandrel 36 is moved responsively to such change, it releases the balls. Thus positive locking and unlocking is assured.

Pitch indicating system The pitch changing mechanism heretofore described may be considered as a sort of micrometer in which a certain number of turns of ring gear 55 relative to the propeller shaft 3i) will change the pitch by one degree. It follows that measurement of the differential angle of ring gear 55 with respect to the shaft will provide a means for measuring and indicating the blade pitch with a high degree of accuracy. The need for accurate pitch indication becomes apparent when it is considered that a change of pitch angle of one degree may alter the speed of the vessel by a knot or more, assuming the revolutions to be held constant. In practice, however, the ability to change the engine speed makes the pitch setting less critical than it would be otherwise.

Means are provided by the invention for indicating the pitch angle accurately. This means includes a sprocket cut in the outer periphery of ring gear 55 and another equal sprocket 35 fixed to the flange of propeller coupling .31. These sprockets drive a pair of equal sprockets 71, 72 respectively of differential angle reducer DAR by means of roller chains 73, 74. Differential angle reducer DAR, described in detail 1n my co-pending application Ser. No. 433,991, filed March 9, 1942, now forfeited, has two input shafts Sl. and S2 and a single output shaft S3; and is provided with novel differential planetary gearing whereby the output shaft is driven in greatly reduced proportion to the differential rotations of the input shafts, say at a reduction of 60:1. Thus under normal conditions when the pitch is not being changed, the output shaft does not rotate, but when the pitch is being changed the output shaft rotates slowly in one direction or the other inaccordance with the pitch change. The output shaft drives a mechanical pitch indicator P1 of dial and pointer type, preferably located on the instrument panel, by means of a flexible tachometer drive in well-known manner.

Pitch control system .For best results, a pitch control system should be simple, precise, flexible and easy to manipulate.

For a small change of pitch, a slow change of pitch in combination with an accurate pitch indicator as described will obviously facilitate attaining a desired pitch setting on the first try. But for emergencies, the main objective is to change the pitch so as to stop the vessel as rapidly as possible. A point to be considered in connection with CRP propellers is that it has been shown by Rudenberg that the shortest distance for stopping a vessel is obtained by reducing the pitch gradually, thereby avoiding loss of reverse thrust due to cavitation and churning. It follows that there is an optimum rate of pitch reversal for quick stopping which works out t be about seconds for motor boats.

`Hydraulic brakes are unsurpassed in providing great flexibility and range of control. This fact, together with the inherent simplicity and ease of installation of hydraulic control, makes hydraulic brakes the control apparatus of choice in the system of the invention, altho mechanical brakes could of course be used.

Referring now to the schematic diagram of the control system shown in Fig. 8, the hydraulic brakes are controlled by a two-cylinder, lever actuated hydraulic transmitter HT. Each cylinder supplies hydraulic uid to operate one set of hydraulic brakes. The hydraulic transmitter is connected operatively to the hydraulic brakes by small copper tubing and tube fittings of commercial type, according to automotive practice.

It is readily seen from the diagram that the pitch control handle PC can be moved in one direction F to increase the pitch and in the other direction R to reverse the pitch. The degree of application of the brakes can be appreciated by the feel of the handle PC. Thus the control system is of the double-sensory type, whereby the operator can feel the degree of control which he is exerting and can see at any time the status of the controlled element. It is of course well established that a double-sensory control system promotes the highest degree of skill in manipulating controls, as for example in steering a boat.

It is thought evident without further discussion that the control system described is Well adapted to the purpose of pitch control and will facilitate skillful handling of a boat equipped with the propeller system of the invention. Further, that the control system, which utilizes well developed commercial apparatus, meets the practical requirements of simplicity, reliability, low cost and ease of installation.

While I have described my invention in detail in its present preferred embodiment, it Will be obvious to those skilled in the art, after understanding my invention, that various changes and modifications may be made therein Without departing from the spirit or scope thereof. The appended claims are therefore intended to cover all such modifications and changes.

I claim as my invention:

1. In a controllable reversible pitch marine propeller system including a power drive shaft, the combination of a tubular propeller shaft; a coupling assembly connecting said drive shaft in driving relation to said propeller shaft; a propeller assembly fixed to the end of said propeller shaft including a hub having an axial bore and blades, each provided with a pair of diametral crank pins, journaled for axial rotation in said hub and a cam member axially translatable in said bore having a screwthreaded axial bore and grooves engaging said crank pins thereby to apply a torque couple to each pair uponA translation of said cam member; a rotatable torque shaft extending coaxially thru said propeller shaft and having a screw-threaded portion mating with said cam member to translate same upon rotation therein; torque-amplifying planetary gearing carried bodily on the outside of said coupling assembly and connected in driving relation to said torque shaft; a pair of brakes for applying selective braking action to said planetary gearing thereby to cause said gearing to drive said torque shaft in one or the other rotary direction relative to said propeller shaft; pitch control means for actuating said brakes selectively thereby to change the pitch of said blades; means for indicating said pitch; and an automatic pitch limit device mounted entirely Within said coupling assembly for selectively blocking the action of said planetary gearing, thereby to limit the pitch change to a predetermined working range.

2. A controllable reversible pitch propeller system having a power drive shaft and combining, a tubular propeller shaft; a coupling assembly connecting said shafts including a hollow hub and blades journaled therein for axial rotation; a mechanical movement including a screw-jack operatively mounted in said hub for applying a torque couple to rotate said blades axially; a torque shaft rotatable in said propeller shaft and connected to drive said screw jack; torque amplifying planetary gearing mounted bodily on the outside of said coupling assembly and connected in driven relation to said drive shaft and in driving relation to said torque shaft; a pair of brakes adapted to apply alternate braking action to said gearing, thereby to cause said gearing to drive said torque shaft in one rotary direction or the other relative to said propeller shaft; control means for selectively actuating said brakes; mechanical pitch indicating means driven jointly by said coupling assembly and said planetary gearing; and an automatic pitch limit device mounted entirely Within said coupling assembly and actuated by said planetary gearing to partially block the action of said planetary gearing, thereby nullifying the action of said brakes so as to limit the change of pitch to a predetermined range. f

References Cited in the iile of this patent UNITED STATES PATENTS Number Name Date 1,396,325 Gloor Nov. 8, 1921 1,656,019 Roberts Jan. 10, 1928 1,898,697 Thompson Feb. 21, 1933 2,007,417 Aivaz July 9, 1935 2,108,660 Farrell Feb. 15, 1938 2,187,754 Ruths et al. Jan. 23, 1940 2,392,341 Squier Ian. 8, 1946 2,423,191 Kopp July 1, 1947 FOREIGN PATENTS Number Country Date 760 Great Britain 1907 12,595 Great Britain 1908 14,525 Great Britain 1903 

